Finding brake parts to maintain my 2-ton dump has been a joy, but thankfully the crusty old guy at my local Napa that knows what book to look in hasn't retired, yet. Living in an agricultural community has it's perks too, between farm trucks and old tractors the local truck shop sees a lot of off the wall jobs and has been a great help.
I rebuilt everything from the pedal to the shoes, even chased down a NOS hydrovac, but finding replacement drums? Fat chance! Fronts are OK but my rear drums are in need. Still, even with 5 yards of damp soil in the box the factory system stopped way better than I expected, and empty it would stop like right now.
A dual circut upgrade to disc would be a dream, when parked too long seems like one of the 4 rear slaves leaks and drains the system, it gets *real* exciting when I suck air into the system, not a fan! Not hauling w her any more, but 9,000lbs of not stopping,...

Moot point at the moment, no place to work on her and broke a line last time I was trying to do a quick hone/rebuild on the culprit slave.